Vertical-offset coater and methods of use

ABSTRACT

The invention provides a coater, and methods of using the coater, for depositing thin films onto generally-opposed major surfaces of a sheet-like substrate. The coater has a substrate transport system adapted for supporting the substrate in a vertical-offset configuration wherein the substrate is not in a perfectly vertical position but rather is offset from vertical by an acute angle. The transport system defines a path of substrate travel extending through the coater. The transport system is adapted for conveying the substrate along the path of substrate travel. Preferably, the transport system includes a side support for supporting a rear major surface of the substrate. The preferred side support bounds at least one passage through which coating material passes when such coating material is deposited onto the substrate&#39;s rear major surface. Preferably, the coater includes at least one coating apparatus (e.g., which is adapted for delivering coating material) on each of two sides of the path of substrate travel. The coating apparatuses preferably are adapted for depositing coatings onto both of the generally-opposed major surfaces of the substrate in a single pass of the substrate along the path of substrate travel.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a divisional application of U.S. patentapplication Ser. No. 11/197,651, titled VERTICAL-OFFSET COATER, filedAug. 4, 2005, which itself claims priority to provisional US patentapplication filed Aug. 12, 2004 and assigned Ser. No. 60/600,923, thecontents of both of which are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention provides methods and equipment for depositingcoatings on glass and other sheet-like substrates.

BACKGROUND OF THE INVENTION

A wide variety of coatings can be applied to glass sheets and othersheet-like substrates to provide the substrates with desired propertiesand characteristics. Well known coating types include low-emissivitycoatings, solar control coatings, hydrophilic coatings, hydrophobiccoatings, photocatalytic coatings, photovoltaic coatings, electrochromiccoatings, mirror coatings, and antireflective coatings. In some cases,it is desirable to apply coatings to both sides of a sheet-likesubstrate. For example, a substrate may be provided with alow-emissivity coating on one side and a photocatalytic coating on theother side. Alternatively, a substrate may be provided with alow-emissivity coating on one side and a hydrophobic coating on theother side. Further, a substrate may be provided with a low-emissivitycoating on one side and a hydrophilic coating (which may or may not bephotocatalytic) on the other side. Still further, a substrate may beprovided with a photocatalytic coating on one side and a mirror coatingon the other side. Many further variants are possible.

When coatings are applied to both sides of a substrate, the coatingdeposition can be performed, for example, using a coater that is adaptedonly for downward deposition (e.g., using a coater adapted only forconventional downward sputtering). This can involve applying a coatingto one side of the substrate in a first pass through the coater, andthereafter applying another coating to the other side of the substratein a second pass through the coater, flipping the substrate between thefirst and second passes. Alternatively, one side of a substrate can becoated by conveying the substrate through a first coater (e.g., a coateradapted for pyrolytic deposition), and the other side of the substratecan be coated by subsequently conveying the substrate through a secondcoater (e.g., a coater adapted for sputter deposition). Such processes,however, are less than ideal in terms of efficiency and simplicity.

Attempts have been made to provide more efficient methods for coatingboth sides of a sheet-like substrate, generally by coating both sides ofthe substrate in a single pass through a single coating apparatus.Reference is made to U.S. Pat. No. 5,683,561 (Hollars et al.) and U.S.Pat. No. 5,762,674 (Maltby, Jr. et al.), the entire contents of each ofwhich are incorporated herein by reference. Particularly usefultechnology for coating both sides of a substrate is disclosed inInternational Patent Application PCT/US99/02208 (InternationalPublication No. WO 00/37377 (Bond et al.)), the entire contents of whichare incorporated herein by reference.

While these recent technologies show great improvement over traditionalmethods, there is a need for other sophisticated technologies in whichcoatings are applied to both sides of a substrate. For example, with therapid evolution of new coatings and ongoing advances in depositionequipment, there is a need for other efficient methods in which bothsides of a substrate can be coated with high quality coatings. There isa particular need for technology in which both sides of a large-areasubstrate can be provided with pinhole-free coatings. This is especiallytrue with respect to glass sheets and other large-area substratesdesigned for architectural and automotive glass applications.

SUMMARY OF THE INVENTION

In certain embodiments, the invention provides a method for depositingthin films onto generally-opposed major surfaces of a sheet-likesubstrate. The method comprises providing a coater having a substratetransport system adapted for maintaining the substrate in avertical-offset configuration wherein the substrate is not in aperfectly vertical position but rather is offset from vertical by anacute angle. The transport system defines a path of substrate travelextending through the coater. The transport system includes a sidesupport for supporting a rear surface that is one of the major surfacesof the substrate. The side support bounds a passage through whichcoating material passes when such coating material is deposited onto thesubstrate's rear major surface. Preferably, the coater includes at leastone coating apparatus on each of two sides of the path of substratetravel. The method comprises: positioning the substrate on the transportsystem such that the substrate is maintained in the vertical-offsetconfiguration; conveying the substrate along the path of substratetravel; and operating the coating apparatuses to deposit coatings ontoboth generally-opposed surfaces of the substrate in a single pass of thesubstrate along the path of travel.

In certain embodiments, the invention provides a coater for depositingthin films onto generally-opposed major surfaces of a sheet-likesubstrate in a single pass of the substrate through the coater. Thecoater has a substrate transport system adapted for supporting thesubstrate in a vertical-offset configuration wherein the substrate isnot in a perfectly vertical position but rather is offset from verticalby an acute angle. The transport system defines a path of substratetravel extending through the coater. The transport system is adapted forconveying the substrate along the path of substrate travel whilemaintaining the substrate in the vertical-offset configuration. Thetransport system includes a side support for supporting a rear surfacethat is one of the major surfaces of the substrate. The side supportbounds a passage through which coating material passes when such coatingmaterial is deposited onto the substrate's rear major surface. Thecoater includes at least one coating apparatus on each of two sides ofthe path of substrate travel. The coating apparatuses is adapted fordepositing coatings onto both of the generally-opposed major surfaces ofthe substrate in a single pass of the substrate along the path ofsubstrate travel.

In certain embodiments, the invention provides a method for depositingthin films onto generally-opposed major surfaces of a sheet-like,large-area substrate using a coater. In these embodiments, thelarge-area substrate has a major dimension of at least about 1 meter.The method comprises positioning the substrate on a substrate transportsystem such that the substrate is maintained in a vertical-offsetconfiguration wherein the substrate is not in a perfectly verticalposition but rather is offset from vertical by an acute angle. Thetransport system defines a path of substrate travel extending throughthe coater. The transport system has a side support comprising aplurality of support surfaces for supporting a rear major surface thatis one of the major surfaces of the substrate. The side support bounds aplurality of passages each located between at least two of the supportsurfaces. The coater includes at least one coating apparatus on each oftwo sides of the path of substrate travel. The substrate is conveyedalong the path of substrate travel while being maintained in thevertical-offset configuration. The coating apparatuses are operated soas to deposit coating material substantially entirely over both majorsurfaces of the substrate in a single pass of the substrate through thecoater, some of the coating material being delivered through thepassages and onto the substrate's rear major surface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic end view of a coater in accordance with certainembodiments of the invention;

FIG. 2 is a schematic front view of a side support in accordance withcertain embodiments of the invention;

FIG. 3 is a schematic front view of a substrate being conveyed along atransport system extending through a coater in accordance with certainembodiments of the invention;

FIG. 4 is a schematic end view of a coater in accordance with certainembodiments of the invention;

FIG. 5 is a schematic front view of a side support in accordance withcertain embodiments of the invention;

FIG. 6 is a schematic front view of a substrate being conveyed along atransport system extending through a coater in accordance with certainembodiments of the invention;

FIG. 7 is a schematic front view of two substrates being conveyed alonga transport system extending through a coater in accordance with certainembodiments of the invention;

FIG. 8 is a schematic end view of a coater in accordance with certainembodiments of the invention;

FIG. 9 is a schematic front view of a side support in accordance withcertain embodiments of the invention; and

FIG. 10 is a schematic perspective view of a transport system inaccordance with certain embodiments of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following detailed description is to be read with reference to thedrawings, in which like elements in different drawings have likereference numerals. The drawings, which are not necessarily to scale,depict selected embodiments and are not intended to limit the scope ofthe invention. Skilled artisans will recognize that the examplesprovided herein have many useful alternatives that fall within the scopeof the invention.

A variety of substrates are suitable for use in the present invention.In most cases, the substrate 10 is a sheet of transparent material(i.e., a transparent sheet). However, the substrate 10 is not requiredto be transparent. For example, opaque substrates may be useful in somecases. It is anticipated, however, that for most applications, thesubstrate will comprise a transparent or translucent material, such asglass or clear plastic. In many cases, the substrate 10 will be a glasspane. A variety of glass types can be used, and soda-lime glass isexpected to be preferred.

Substrates of various sizes can be used in the present invention.Commonly, large-area substrates are used. Certain embodiments involve asubstrate 10 having a major dimension (e.g., a width or length) of atleast about 0.5 meter, preferably at least about 1 meter, perhaps morepreferably at least about 1.5 meters (e.g., between about 2 meters andabout 4 meters), and in some cases at least about 3 meters.

Substrates of various thicknesses can be used in the present invention.Commonly, substrates with a thickness of about 1-5 mm are used. Someembodiments involve a substrate 10 with a thickness of between about 2.3mm and about 4.8 mm, and perhaps more preferably between about 2.5 mmand about 4.8 mm. In some cases, a sheet of glass (e.g., soda-limeglass) with a thickness of about 3 mm is used.

Generally, the invention provides a vertical-offset coater and methodsof using the coater to deposit coatings onto a sheet-like substrate. Incertain embodiments, the coater and methods are used to deposit coatingsonto generally-opposed surfaces of the substrate in a single pass of thesubstrate through the coater. In such embodiments, the manufacturer isable to apply high quality coatings to both major surfaces of thesubstrate in a very efficient manner. The resulting coatings arelargely, if not entirely, free of unwanted pinholes and similar defects.

Thus, in certain embodiments, the invention provides a coater fordepositing thin films onto generally-opposed major surfaces of asheet-like substrate in a single pass of the substrate through thecoater. The coater includes one or more deposition chambers, eachpreferably having a ceiling 22, floor 24, and one or more side walls 26.

As is perhaps best illustrated in FIGS. 3, 6-7, and 10, the coater 20includes a substrate transport system 170. Preferably, the transportsystem 170 is adapted for maintaining the substrate in a vertical-offsetconfiguration wherein the substrate 10 is not in a perfectly verticalposition but rather is offset from vertical by an acute angle α. Thevertical-offset configuration of the substrate is perhaps bestappreciated with reference to FIG. 4. The angle α is preferably lessthan about 25 degrees, perhaps more preferably less than about 15degrees, and perhaps optimally less than about 10 degrees. In certainembodiments, the angle α is between about 5 degrees and about 10degrees. One embodiment involves an angle α of about 7 degrees.

The transport system 170 defines a path of substrate travel 100extending through the coater 20. Preferably, the path of substratetravel 100 extends between a coater inlet 115 and a coater outlet 120,as is best seen in FIG. 7. The transport system 170 preferably isadapted for moving (e.g., conveying) the substrate 10 along the path ofsubstrate travel 100 while maintaining the substrate 10 in thevertical-offset configuration. Thus, the transport system 170 preferablyincludes a side support 30 and a bottom conveyor 40.

When the substrate 10 is conveyed through the coater 20 on the transportsystem 170, the substrate's rear major surface 14 is supported by (e.g.,is in direct physical contact with) the side support 30. The sidesupport 30 can be provided in a variety of different forms. For example,it can comprise a framework 132 and/or a platen 39. FIGS. 1-3 and 8-9exemplify certain embodiments wherein the side support comprises aplaten 39, and FIGS. 4-7 and 10 exemplify certain embodiments whereinthe side support comprises a framework 132.

As is perhaps best understood with reference to FIGS. 2, 5, 9, and 10,the side support 30 preferably bounds at least one passage 34 throughwhich coating material passes when such coating material is depositedonto the substrate's rear surface 14. With reference to FIG. 1 in viewof FIG. 2, for example, it can be appreciated that the shadowed area 34is space defining such a passage 34. In some embodiments, the sidesupport 30 bounds a plurality of passages 34 of the described nature.For example, the side support 30 may bound a series of passages 34 pastwhich the substrate 10 is conveyed sequentially as it 10 moves along thepath of substrate travel 100. In certain embodiments, the side support30 defines at least one passage 34 having a vertical dimension that isat least as great as, and perhaps optimally greater than, a verticaldimension of the substrate 10 when the substrate is in thevertical-offset configuration, such that it is possible to achievefull-area coating of the substrate's rear major surface 14.

The side support 30 preferably comprises a plurality of rotatable bodies36 adapted to roll against the substrate's rear surface 14 when thesubstrate 10 is conveyed along the path of substrate travel 100. Therotatable bodies 36 preferably are mounted in a fixed position relativeto (e.g. on) the side support 30. For example, each rotatable body 36preferably is mounted in a fixed location where it is adapted to rotateabout a vertical or generally vertical axis. As shown in FIG. 2, theside support 30 can comprise a plurality of rotatable wheels 36. Forexample, one or more of the rotatable bodies 36 can be wheels. Suchwheels 36 can be provided as an arrangement (a matrix, line, etc.)wherein the wheels 36 are spaced vertically and/or horizontally from oneanother. Preferably, such wheels 36 are oriented so their direction ofrotation corresponds to the desired direction of substrate travel (e.g.,such wheels 36 preferably are adapted for rotation about a common axis).In FIG. 2, each wheel 36 is mounted on a wall section 32 of the sidesupport 30. This exemplifies a class of embodiments wherein a passage 34(or a portion of a passage 34) is located between adjacent wall sections32 and/or adjacent wheels 36 of the side support 30.

Preferably, the side support 30 is mounted inside the coater 20. Incertain embodiments, the side support 30 is mounted at an angle ∈ offsetfrom vertical. In these embodiments, when the substrate's rear surface14 is supported by (e.g., rests directly against support surfaces of)the side support 30, the substrate 10 is maintained in thevertical-offset configuration. The side support 30 (e.g., a platen orgenerally-planar framework thereof) desirably is mounted at an angle ∈offset from vertical by less than 90 degrees. Preferably, the angle ∈ isless than about 25 degrees, perhaps more preferably less than about 15degrees, and perhaps optimally less than about 10 degrees. In certainpreferred embodiments, the angle ∈ is substantially equal to the angle αof the substrate when in the vertical-offset configuration.

In embodiments wherein the side support 30 comprises a platen 39, theplaten preferably bounds the passage(s) 34 through which coatingmaterial passes when the substrate's rear surface 14 is coated. Theplaten 39 can comprise a generally-planar wall. In such embodiments, theplaten can comprise a wall that defines (e.g., entirely surrounds)apertures that serve as the passage(s) 34. Alternatively oradditionally, the platen can comprise a wall formed, at least in part,by a plurality of wall sections 32. The wall sections 32 cancollectively bound the passage(s) 34. Embodiments of this nature areexemplified in FIGS. 2 and 9. If so desired, the platen 39 can compriseadjacent wall sections 32 separated by a gap (optionally extendingentirely across the wall, e.g., generally vertically) that serves as acoating passage 34. This is perhaps best appreciated with reference toFIG. 9.

In alternate embodiments, the side support 30 comprises a platen 39 thatis mounted in a vertical configuration. One embodiment of this nature isexemplified in FIG. 8. Here, a plurality of rotatable bodies 36 projectvarying distances from the platen 39 such that when the substrate 10 issupported collectively by (e.g., leans directly against) the rotatablebodies 36, the substrate is maintained in the vertical-offsetconfiguration. For example, a series of lower rotatable bodies can bemounted on such a platen so as to extend relatively far from the platen,while a series of upper rotatable bodies can be mounted on such a platento extend a lesser distance from the platen than do the lower rotatablebodies.

As noted above, the side support 30 in some embodiments comprises aframework (e.g., one or more beams, rails, or other frame members) 132.Embodiments of this nature are perhaps best appreciated with referenceto FIGS. 4-7 and 10. In these embodiments, the framework 132 preferablyis provided with (or adjacent) the rotatable bodies 36. In embodimentslike those exemplified in FIG. 5, the side support 30 includes one ormore rollers 36 adapted to roll against the substrate's rear majorsurface 14 when the substrate is conveyed along the path of substratetravel 100. Such rollers are preferably oriented so their direction ofrotation corresponds to the desired direction of substrate travel. Theillustrated rollers each comprise an elongated cylindrical body. In FIG.4, each roller is mounted for rotation about an axis that is offset fromvertical by an angle ∈ of less than 90 degrees. Preferably, the angle ∈is less than about 25 degrees, perhaps more preferably less than about15 degrees, and perhaps optimally less than about 10 degrees. In someembodiments, the axis of rotation of each such roller is offset fromvertical by an angle that is substantially equal to, or substantiallyequal to, the angle α of the substrate 10 when the substrate is in thevertical-offset configuration. In one such embodiment, this common angleis about 7 degrees.

When the substrate 10 is supported by (e.g., leans against) the sidesupport 30, at least some of the substrate's rear surface 14 is exposed(e.g., to coating material being delivered to the substrate's rearsurface from a rear coating apparatus 54 further from the substrate 10than the side support 30) by the passage(s) 34. As noted above, coatingmaterial can be deposited through the passage(s) 34 and onto thesubstrate's rear surface 14. This is possible due to the relativepositioning of the substrate 10, the side support 30 (and the passage(s)34 in particular), and the rear coating apparatus(es) 54. Preferably,the side support (e.g., at least those portions adapted for supportingthe substrate's rear surface during conveyance) is positioned betweenthe path of substrate travel 100 and at least one rear coating apparatus54. Similarly, when the substrate is in a desired coating position onthe transport system (i.e., when the substrate is being coated byoperating at least one rear coating apparatus), the side support 30preferably is positioned between the substrate 10 and at least one rearcoating apparatus 54. This is perhaps best appreciated with reference toFIGS. 1 and 4. The passage(s) 34 allow coating to be deposited onto thesubstrate's rear surface 14 while the substrate is supported by the sidesupport 30. Preferably, when the substrate 10 is in such a desiredcoating position, at least one rear coating apparatus 54 is aligned witha passage 34 of the side support 30.

The rotatable bodies 36 of the side support 30 preferably comprise(e.g., are formed of) material adapted to withstand vacuum depositionconditions. In some cases, the rotatable bodies 36 comprise (e.g., havean outer surface formed of, consisting essentially of, or at leastcomprising) carbon and/or another carbon-containing material. Carbon isparticularly non-damaging to coated substrates and thus helps preventremoval of, and other damage to, coating on the substrate's rear surfaceduring conveyance of the substrate through the coater.

The transport system 170 preferably includes a bottom conveyor 40adapted for receiving (and supporting) a bottom edge 77 of the substrate10. Preferably, the substrate 10 when positioned on the transport system170 and maintained in the vertical-offset configuration has its bottomedge 77 supported by the bottom conveyor 40 and its rear major surface14 supported by the side support 30. With the substrate so positioned,the bottom conveyor 40 preferably is adapted to move (e.g., convey) thesubstrate 10 through the coater 20 along the path of substrate travel100 (while maintaining the substrate in the vertical-offsetconfiguration).

The bottom conveyor 40 can comprise any device (e.g., a conveyor beltand/or a series of rotatable members) that is adapted to support thesubstrate's bottom edge 77 while allowing the substrate 10 to move alongthe path of substrate travel 100. Preferably, the bottom conveyor 40 ismotorized, such that the conveyor 40 is adapted to drive the substrate10 along the path of substrate travel 100. In some embodiments, theconveyor system 40 comprises a series of rotatable members 144. Therotatable members are preferably positioned along (e.g., entirely along)the path of substrate travel 100. In certain methods of the invention,at least one such rotatable member is made to rotate by energizing amotor operably connected to such member, so that when the bottom edge 77of the substrate 10 rests directly on such member, friction between therotating member and the substrate's bottom edge 77 causes the substrate10 to move along the path of substrate travel 100. Thus, when thesubstrate 10 is conveyed along the path of substrate travel, thesubstrate's bottom edge 77 can optionally be in direct contact with suchrotatable members 144 and/or with a conveyor belt or the like disposedover such rotatable members 144.

In certain embodiments, the bottom conveyor 40 defines a supportplatform 47 that is not perfectly horizontal but rather is offset fromhorizontal H by an angle β of less than 90 degrees. In some embodiments,the angle β is less than about 25 degrees, perhaps more preferably lessthan about 15 degrees, and perhaps optimally less than about 10 degrees.In certain preferred embodiments, the angle β is substantially equal tothe angle α of the substrate 10 when in the vertical-offsetconfiguration.

Thus, certain embodiments involve a support platform 47 that is definedby the bottom conveyor 40 and comprises one or more support surfaces 147on which the substrate's bottom edge 77 is physically supported duringconveyance. In certain embodiments, a conveyor belt defines the supportplatform 47 (and the support surface 147) on which the substrate rests.In other embodiments, surfaces of a series of rotatable members 144collectively define the support platform 147. In some embodiments ofthis nature, each rotatable member 144 has a support surface 147, andthe support surfaces 147 of the rotatable members lie in a common plane(e.g., which can optionally be offset from vertical by the angle β).

While certain preferred embodiments of the invention involve a bottomconveyor 40 that is not perfectly horizontal, the invention includesembodiments wherein the bottom conveyor 40 simply lies in a horizontalplane. In these embodiments, the substrate preferably is maintained inthe vertical-offset configuration when it is conveyed along the path ofsubstrate travel (e.g., the side support 30 can be at an inclineappropriate to support the substrate in the vertical-offsetconfiguration). Embodiments of this nature may involve front wheels(e.g., adjacent a front portion of the bottom conveyor 40) adapted toengage and support a bottom peripheral region of the substrate's frontmajor surface 12. Exemplary front wheels 242 are shown in FIG. 10.

In certain embodiments, the substrate 10 is a sheet of glass having itsbottom edge 77 supported by the bottom conveyor 40 while the substrateis conveyed along the path of substrate travel. In some cases, othersheets of glass are also positioned on the bottom conveyor 40, thesheets of glass being spaced apart from one another on the bottomconveyor 40 and conveyed in such a spaced-apart arrangement. Eachsubstrate 10 is typically conveyed through the chamber 20 at a speed ofbetween about 100 and about 500 inches per minute. Thus, in certainmethods, the substrate is conveyed along the path of substrate travel,and this conveyance involves moving the substrate at a speed of betweenabout 100-500 inches per minute. While the illustrated bottom conveyor40 comprises a plurality of rotatable members 144, various types ofconveyor systems can be used.

The invention is particularly advantageous for processing large-areasubstrates, such as glass sheets for architectural and automotive glassapplications. Thus, in certain methods of the invention, the substrate10 conveyed through the coater 20 is a large-area substrate having amajor dimension of at least about 1 meter.

The coater 20 includes at least one coating apparatus on each of twosides of the path of substrate travel 100. Preferably, at least onecoating apparatus 52 is provided on a front side of the path ofsubstrate travel. This front coating apparatus 52 is adapted fordepositing film onto the substrate's front major surface 12. Conjointly,at least one coating apparatus 54 preferably is provided on a rear sideof the path of substrate travel. This rear coating apparatus 54 isadapted for depositing film onto the substrate's rear major surface 14.Preferably, the rear coating apparatus 54 is behind the side support 30(e.g., the rear coating apparatus 54 and the path of substrate travelpreferably are on opposite sides of the side support) and is configuredfor emitting coating material that passes through the passage(s) 34 ontothe substrate's rear major surface 14. This is perhaps best appreciatedwith reference to FIGS. 1 and 4. In some embodiments, a single coatingapparatus is on each side of the path of substrate travel 100, althoughany number of coating apparatuses can be provided on each side of thispath 100. Preferably, each coating apparatus (or at least the portionadapted for emitting coating material) is mounted inside the coater 20.

The coater 20 is adapted for carrying out one or more thin filmdeposition processes. In preferred embodiments, the coater 20 comprisesa vacuum deposition chamber in which a controlled vacuous environmentcan be established. In such embodiments, the vacuum deposition chamberis adapted for use at (e.g., is adapted for establishing and maintainingtherein) a total gas pressure of less than about 140 torr., morepreferably less than about 0.1 torr., and perhaps optimally betweenabout 1 mtorr. and about 0.1 torr. (e.g., between about 1 mtorr. andabout 30 mtorr.). Thus, the coater 20 preferably has gas delivery andpumping systems adapted for establishing and maintaining such pressures.In certain embodiments, the coater 20 is adapted for carrying out atleast one vacuum deposition process (e.g., selected from the groupconsisting of sputtering, chemical vapor deposition, and ion-assisteddeposition).

In certain embodiments, the coater 20 comprises at least one vacuumdeposition chamber and at least one of the coating apparatuses 52, 54 isa vacuum deposition device. Each such vacuum deposition devicepreferably is mounted (at least in part) inside the coater 20 at alocation on a desired side of the path of substrate travel 100. In somecases, each such device is adapted for emitting coating material in agenerally sideways fashion onto a desired major surface of thevertically-offset substrate.

In certain embodiments, the coater 20 comprises at least one sputterdeposition chamber and at least one of the coating apparatuses 52, 54comprises a sputtering target. In such embodiments, the sputteringtarget can be cylindrical or planar. Preferably, each such sputteringtarget includes a magnet assembly adapted to facilitate magnetronsputtering. In certain preferred embodiments, the coater 20 includes asputtering target mounted adjacent to (e.g., aligned with) a passage 34such that bombarding the target with ions causes particles of sputteredmaterial to be ejected from the target through the passage 34 and ontothe substrate's rear major surface 14.

In certain embodiments, the coater 20 comprise at least one chemicalvapor deposition (CVD) chamber and at least one of the coatingapparatuses 52, 54 comprises a CVD device. Each such CVD device cancomprise a gas delivery system adapted for delivering precursor gas intothe coater. Preferably, each such device comprises a gas-delivery outletinside the coater, such that from the precursor gas coating materialcondenses upon the substrate 10. In more detail, each such CVD devicewill typically comprise a gas supply from which precursor gas isdelivered through a gas line, out of the gas outlet, and into thechamber. If so desired, one or more plasma-enhanced CVD devices can beused. In embodiments wherein a CVD device is used to coat thesubstrate's rear surface 14, the device can be configured in the chamberso as to direct precursor fluid (e.g., gas and/or liquid) through apassage 34 and onto the substrate's rear surface 14.

In certain embodiments, the coater 20 is adapted for ion-assisteddeposition and at least one of the coating apparatuses 52, 54 comprisesan ion gun. Generally, such an ion gun can be adapted for carrying outany desired ion-assisted deposition (IAD) process. For example, such anion gun can be adapted for direct film deposition. Alternatively, suchan ion gun can be part of an ion beam sputter deposition sourcecomprising a sputtering target against which the ion gun acceleratesions, such that atoms of the target material are ejected from the targettoward a desired major surface of the substrate. Other types of IADmethods can also be used.

In many cases, the coater 20 will comprise a series of depositionchambers. FIG. 7 exemplifies one such embodiment. The coater 20 cancomprise virtually any number of chambers. Thus, the coater may have asingle deposition chamber or it may comprise a line of connecteddeposition chambers (i.e., a coating line). In more detail, such acoating line may comprise a series of deposition chambers aligned andconnected so that a substrate maintained in the vertical-offsetconfiguration can be conveyed sequentially through the chambers of thecoater. During coating deposition, the substrate is typically conveyedthrough all the deposition chambers of such a coater. It is to beappreciated that the coater 20 can include a plurality of depositionchambers aligned and connected in this manner, regardless of theparticular deposition processes that are performed in such chambers.

In embodiments wherein the coater 20 includes more than one depositionchamber, the chambers are typically connected such that the path ofsubstrate travel 100 extends through each of the deposition chambers.FIG. 7 exemplifies an embodiment wherein the path of substrate travel100 extends between a coater inlet 115 and a coater outlet 120.Preferably, the path of substrate travel 100 extends horizontallythrough the coater 20.

The coater 20 can include different deposition chambers adapted forcarrying out different deposition processes. For example, the coater caninclude one or more chambers in which sputtering is performed and one ormore chambers in which ion-assisted deposition is performed. Further,the coater 20 can include one or more chambers in which sputtering isperformed and one or more chambers in which chemical vapor deposition isperformed. Various alternatives of this nature will be apparent toskilled artisans given the present teaching as a guide.

The invention also provides methods for depositing thin films ontogenerally-opposed major surfaces of a sheet-like substrate. There isprovided a coater 20 of the described nature. Preferably, the coater hasa substrate transport system adapted for maintaining the substrate in avertical-offset configuration wherein the substrate is not in aperfectly vertical position but rather is offset from vertical by anacute angle. The preferred transport system defines a path of substratetravel extending through the coater. The preferred transport system alsoincludes a side support for supporting a rear surface that is one of themajor surfaces of the substrate. The preferred side support bounds apassage through which coating material passes when such coating materialis deposited onto the substrate's rear major surface. The coater 20desirably includes at least one coating apparatus on each of two sidesof the path of substrate travel.

Preferably, at least one of the coating apparatuses is a rear coatingapparatus, and the operation of the coating apparatuses involvesoperating the rear coating apparatus(es) so as to deliver coatingmaterial through the passage(s) 34 and onto the substrate's rear majorsurface 14. In certain optional embodiments, the side support 30 boundsa plurality of passages and such coating material is delivered throughthese passages and onto the substrate's rear major surface 14. In someparticularly preferred embodiments, one of the coating apparatuses is arear coating apparatus that is aligned with a desired passage 34, theconveyance of the substrate along the path of substrate travel involvesbringing the substrate into a position where the desired passage 34 isbetween this rear coating apparatus and the substrate's rear majorsurface 14, and the operation of the coating apparatuses involvesoperating this rear coating apparatus so as to deliver coating materialthrough the desired passage 34 and onto the substrate's rear majorsurface 14.

The present methods, in certain embodiments, include positioning thesubstrate on the transport system such that the substrate is maintainedin the vertical-offset configuration. The substrate 10 is conveyed alongthe path of substrate travel 100 (preferably while maintained in thevertical-offset configuration). In preferred methods, the coatingapparatus(es) are operated (e.g., as the substrate is being conveyed) soas to deposit coatings onto both generally-opposed major surfaces of thesubstrate in a single pass of the substrate along the path of substratetravel.

The preferred transport system includes a bottom conveyor adapted forreceiving a bottom edge of the substrate, wherein the substrate whenpositioned on the transport system and maintained in the vertical-offsetconfiguration has its bottom edge supported by the bottom conveyor andits rear major surface supported by the side support. Thus, in preferredmethods, the substrate is maintained in the vertical-offsetconfiguration during the conveyance of the substrate along the path ofsubstrate travel.

In certain preferred methods, the coatings are deposited entirely overboth major surfaces of the substrate to achieve full-area coating ofboth major surfaces. Further, one of the coatings preferably is a rearcoating on the rear major surface of the substrate, and this rearcoating preferably comes into contact with the side support 30 duringthe conveyance of the substrate along the path of substrate travel. Asnoted above, the side support preferably comprises a plurality ofrotatable bodies (e.g., wheels in some embodiments) that roll againstthe rear major surface of the substrate during said conveying thesubstrate along the path of substrate travel.

Preferably, at least one coating apparatus 54 behind the side support 30is operated to deliver coating material through at least one passage 34(bounded by the side support 30) and onto the rear surface 14 of thesubstrate 10. In some cases, at least one of the coating apparatuses(e.g., at least one rear coating apparatus 54) is a sputtering targetand is operated by bombarding the target with ions so as to ejectparticles of sputtered material from the target, through at least onepassage 34, and onto the rear surface 14 of the substrate. In theseembodiments, the operation of the coating apparatus(es) involvesbombarding a rear target with ions so as to eject particles of sputteredmaterial from the target, through the passage(s) 34, and onto thesubstrate's rear major surface 14. In some preferred embodiments, thecoater 20 includes both front 52 and rear 54 coating apparatuses thatcomprise sputtering targets and the apparatuses are operated bybombarding the front and rear targets with ions so as to eject particlesof sputtered material: (1) from at least one front target towards (andonto) the substrate's front surface 12; and (2) from at least one reartarget, through at least one passage 54, and onto the rear substrate'srear surface 14.

As noted above, the coater 20 in certain embodiments comprises a vacuumdeposition chamber. In related methods of operating such a coater 20, acontrolled vacuous environment is maintained in such vacuum chamberduring the operation of the coating apparatuses.

In certain embodiments, the coatings deposited onto the major surfaces12, 14 of the substrate each have a total physical thickness of lessthan about 2000 angstroms. In some cases, the coating deposited on oneof the major surfaces has a greater total physical thickness than thecoating deposited on the other major surface. For example, the coatingapparatuses 52, 54 can be operated so as to deposit: (1) a first coatingon the substrate's front surface 12; and (2) a second coating on thesubstrate's rear major surface 14, and the front coating can optionallybe applied at a greater thickness than the rear coating, or vice-versa.Any desired coatings can be deposited.

In certain preferred embodiments, a first of the coatings is a rearcoating on the rear major surface 14 of the substrate 10 and the othermajor surface of the substrate is a front major surface 12, and a secondof the coatings is a front coating on the front major surface 12 of thesubstrate. In the present preferred embodiments, there is provided amethod in which the rear coating is applied at a lesser thickness thanthe front coating. In some embodiments of this nature, the totallyphysical thickness of the rear coating is less than about 500 angstroms,perhaps more preferably less than about 300 angstroms, and perhapsoptimally less than about 200 angstroms. Further, in some embodiments,the coating deposited on the substrate's front surface 12 comprises(e.g., is) a low-emissivity coating. In some embodiments of this nature,the low-emissivity coating comprises at least one silver-containing filmdeposited between two dielectric films. Thus, related methods of theinvention involve depositing, e.g., by operating the front coatingapparatus(es) 52, in sequence moving outwardly from the substrate'sfront surface 12: (1) a dielectric film; (2) a silver-containing film(i.e., a film comprising at least some silver); and (3) a dielectricfilm. Optionally, the method involves depositing in such sequence: (1) adielectric film; (2) a silver-containing film (i.e., a film comprisingat least some silver); (3) a dielectric film; (4) a silver-containingfilm; and (5) a dielectric film. In such embodiments, each film cancomprise one or more film layers, film regions, etc.

In certain alternate embodiments of the invention, only the rear majorsurface 14 of the substrate 10 is coated by operating one or more rearcoating apparatuses 54 (e.g., front coating apparatus(es) can be omittedor simply not used).

While preferred embodiments of the invention have been described, itshould be understood that numerous changes, adaptations andmodifications can be made therein without departing from the spirit ofthe invention and the scope of the appended claims.

What is claimed is:
 1. A method for sputtering thin films ontogenerally-opposed major surfaces of a glass sheet substrate having a topedge and a bottom edge, the method comprising: providing a coater havinga substrate transport system adapted for maintaining the glass substratein a vertical-offset configuration wherein the substrate is offset fromvertical by an acute angle between about 5 degrees to less than about 25degrees, the substrate transport system defining a path of substratetravel extending through the coater, the substrate transport systemincluding a side support for supporting a rear surface that is one ofthe major surfaces of the substrate, the side support having a pluralityof wheels adapted to roll directly against the rear major surface of thesubstrate when the substrate is conveyed along the path of substratetravel, at least a portion of a wheel positioned to roll directlyagainst the rear major surface of the substrate proximate the top edgeto support the substrate in the vertical-offset configuration, the sidesupport bounding a passage through which coating material passes whensuch coating material is sputtered onto the substrate's rear majorsurface, the coater including at least one sputtering apparatus on eachof two sides of the path of substrate travel; positioning the substrateon the substrate transport system in the vertical-offset configuration;conveying the substrate along the path of substrate travel in thevertical-offset configuration; operating the sputtering apparatuses soas to sputter coatings onto both generally-opposed major surfaces of thesubstrate in a single pass of the substrate along the path of substratetravel, wherein one of said sputtering apparatuses is a rear sputteringapparatus that is aligned with said passage, wherein the rear sputteringapparatus includes a sputtering target, wherein said conveying thesubstrate along the path of substrate travel involves bringing thesubstrate to a position where said passage is between said rearsputtering apparatus and the substrate's rear major surface, and whereinsaid operating the sputtering apparatuses involves bombarding thesputtering target with ions so as to eject particles of sputteredmaterials from the sputtering target through said passage and onto thesubstrate's rear major surface, thereby sputtering a rear coatingthrough said passage and entirely over the substrate's rear majorsurface to achieve full-area coating of the substrate's rear majorsurface.
 2. The method of claim 1 wherein the rear coating comes intocontact with the side support during said conveying the substrate alongthe path of substrate travel.
 3. The method of claim 1 wherein the sidesupport bounds a plurality of passages and said coating material issputtered through said passages and onto the substrate's rear majorsurface.
 4. The method of claim 1 wherein the coater comprises a vacuumdeposition chamber in which a controlled vacuous environment ismaintained during said operating the sputtering apparatuses.
 5. Themethod of claim 1 wherein each of said coatings are deposited to aphysical thickness of less than about 2,000 angstroms.
 6. The method ofclaim 1 wherein a first of said coatings is the rear coating on the rearmajor surface of the substrate and the other major surface of thesubstrate is a front major surface, and wherein a second of saidcoatings is a front coating on the front major surface of the substrate,the rear coating being applied at a lesser thickness than the frontcoating.
 7. The method of claim 6 wherein the thickness of the rearcoating is less than about 300 angstroms.
 8. The method of claim 6wherein the front coating is a low-emissivity coating.
 9. The method ofclaim 8 wherein the low-emissivity coating comprises at least onesilver-containing film deposited between two dielectric films.
 10. Themethod of claim 1 wherein said acute angle is between about 5 degrees toless than about 10 degrees.
 11. The method of claim 1 wherein saidconveying the substrate along the path of substrate travel involvesconveying the substrate at a speed of between about 100-500 inches perminute.